The mounting (soldering) of components for an electronic device incorporating a solid image capture device is generally performed by surface mount soldering in a reflow oven to achieve high packaging density and small step counts. The components, together with a printed board carrying them, are all put in a reflow oven for heating. Therefore, the method enables large numbers of components to be soldered to a printed board with high density in a single step.
In contrast, a solid image capture element is mounted to a printed board (wiring board) inside an image capture device (digital still camera, video camera, surveillance camera, etc.) after the solid image capture element is sealed temporarily in a resin package.
The solid image capture element can be mounted inside the image capture device by soldering, with a socket, or using a flexible board bridging the element to the device, to name a few major exemplary methods.
The soldering involves an issue of thermal resistance of the solid image capture element. The use of a socket leads to problems such as irregular resin molding and positioning error due to thermal expansion. The use of a flexible board also entails problems: printed lines may break under large bending force while the flexible board is being attached or solder may crack on the flexible board under the pressure applied to the solder.
The socket method is often employed when reduction of cost (number of steps required) is a primary concern because the method allows the socket to be mounted in a reflow oven.
Patent documents 1 to 3 exemplify solid image capture devices mounted to an image capture device.
FIG. 31 is a cross-sectional view of a solid image capture device described in patent document 1. A solid image capture device 200, as disclosed in patent document 1, contains a wiring board 201 and a solid image capture element 202 which is electrically connected to the board 201 via the wire bonds formed by metal elements 203.
FIG. 32 is a cross-sectional view of a solid image capture device described in patent document 2. A solid image capture device 300, as disclosed in patent document 2, contains a wiring board 301 and a solid image capture element 302 which is electrically connected to the board 301 via solder electrodes (not shown) provided on the back of the solid image capture element 302 (opposite to the light receiving surface of the solid image capture element 302).
FIG. 33 is a plan and a cross-sectional view of a solid image capture element in a solid image capture device described in patent document 3. A solid image capture device 400, as disclosed in patent document 3, contains a solid image capture element 402 having an effective pixel area 403 covered with a transparent member 404. The light receiving surface on which the effective pixel area 403 is formed has bonding pads 405. The solid image capture element 402 is electrically connected to a wiring board (not shown) via wire bonding formed between the bonding pads 405 and terminals on the wiring board. Patent document 3 also describes that these solid image capture elements 402 are produced by dicing a semiconductor wafer to which a glass sheet is attached.
In conventional solid image capture devices, the solid image capture element is difficult to remove from the wiring board and place precisely on the wiring board because the solid image capture element needs to be adhered or compressed to the wiring board. Conventional solid image capture devices also require a complex manufacturing process for the same reason.
Specifically, in patent document 1, the solid image capture element 202 is adhered to an element connecting plate 204 interposed between the wiring board 201 and the solid image capture element 202. The wiring board 201 and the solid image capture element 202 are wire bonded by the metal elements 203. It is therefore very difficult to remove the solid image capture element 202 from the wiring board 201.
Furthermore, in the solid image capture device 200, the element connecting plate 204 to which the solid image capture element 202 is adhered is fixed to a lens enclosure 205 by screws (not shown). An elastic body (filter holding member 206) holds down the solid image capture element 202 and a lowpass filter 207 upon the fixing. The solid image capture element 202 could be displaced on the wiring board 201 depending on how tightly the plate 204 is screwed to the enclosure 205. A protection glass 208, as well as the lowpass filter 207, is also needed to protect the solid image capture element 202 because the filter holding member 206 is holding down the solid image capture element 202.
Patent document 2 is utterly silent about how to form the solder electrodes on the back of the solid image capture element 302. These solder electrodes can only provided by means of either electrodes extending through the solid image capture element 302 (“through silicon vias” or TSVs) or wires disposed on a side face of the solid image capture element 302. However, many highly complex steps are additionally needed to form the solder electrodes on the back of the solid image capture element 302. The additional steps reduce production efficiency and increase production cost.
Patent document 3 requires the wire bonding between the bonding pads 405 on the light receiving surface of the solid image capture element 402 and the terminals on the wiring board. Patent document 3 further requires the solid image capture element 402, including the bonding wires, being packaged on the wiring board, so that the solid image capture element 402 can be placed precisely on the wiring board and mounted to the image capture device. The structure makes it very difficult to remove the solid image capture element 402 from the wiring board.    Patent Document 1: Japanese Unexamined Patent Publication No. 2001-21976 (Tokukai 2001-21976; published Jan. 26, 2001)    Patent Document 2: Japanese Unexamined Patent Publication No. 2003-319217 (Tokukai 2003-319217; published Nov. 7, 2003)    Patent Document 3: Japanese Unexamined Patent Publication No. 2004-296453 (Tokukai 2004-296453; published Oct. 21, 2004)